Greasemonkey / Tampermonkey userscript that removes that black banner ("Download App") in top of Messenger.com pages.

Messenger Banner Remover.user.js

// ==UserScript==
// @name        Messenger Banner Remover
// @version     0.1.0
// @namespace   com.gustavosotnas.userjs.messengerbannerremover
// @description Removes that black banner ("Download App") in top of Messenger.com pages.
// @author      Gustavo Moraes
// @copyright   2016+, Gustavo Moraes (https://github.com/gustavosotnas)
// @include     https://www.messenger.com/t/*
// @require     https://code.jquery.com/jquery-2.2.4.min.js
// @icon        https://gist.githubusercontent.com/raw/a39afefbad5267893f6d4639ad3a4dff/messenger_banner_remover_icon.png
// @updateURL   https://gist.githubusercontent.com/raw/a39afefbad5267893f6d4639ad3a4dff/Messenger%20Banner%20Remover.user.js
// @grant       none
// ==/UserScript==

(function() {
    'use strict';

    document.getElementsByClassName("_s15")[0].remove();
})();

messenger_banner_remover_icon.png

messenger_banner_remover_icon.svg

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